Dial



E. K. NAUTH Jan. 5, 1954 DIAL Filed Dec. 4, 1950 INVENTOR Ed av K. Nauzh w ATTORI \IEY Patented Jan. 5, 1954 DIAL Edgar K. Nauth, Kenmore, N. Y., assignor to Sylvania Electric Products Inc., a corporation of Massachusetts Application December 4, 1950, Serial No. 199,080

Claims.

The present invention relates to dials, and, particularly, to dials which are adapted to be edgewise lighted from a relatively concentrated light source. While the invention has general application, it has particular utility in a tuning dial for radio receivers and will be described in that connection.

It is usually desirable to provide an illuminated tuning dial for a radio receiver in order that the receiver may be visually tuned in a darkened room or a room with poor illumination. Numerous arrangements have heretofore been proposed for providing illumination of the tuning dial, among these being edge lighting of the dial. Edge lighting of the dial is usually satisfactory when'accomplished by a plurality of incandescent lamps spaced along the edge of the dial, but it has heretofore been difficult to effect uniform illumination from a single relatively concentrated light source.

It is an object of the present invention to provide a new and improved dial suitable for edge lighting and one having high efficiency of light illumination with relatively uniform illumination from a concentrated light source.

It is a further object of the invention to provide a new dial of the type described having a simple and inexpensive construction adaptable to mass production techniques.

It is an additional object of the invention to provide a new and improved dial of the edge lighted type, adapted for use with a concentrated light source, particularly suitable for a radio receiver and, when used for this purpose, one having a very pleasant and attractive appearance.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring now to the drawing, Fig. 1 illustrates a dial embodying the invention in a particular form particularly suitable for use in a radio receiver; Fig. 2 is a cross-sectional view taken along the plane 2--2 of Fig. 1; and Fig. 3 is an enlarged fragmentary view of a portion of the dial illustrated in Fig. 1 as seen from the back.

Referring now more particularly to Figs. 1 and 2 of the drawing, there is illustrated a radio dial having a planar section In of transparent material With indicia ll thereon. The indicia ll may, for example, be silk-screened on to the rear surface of the section it]. The planar section has (Cl. Mil-124.4)

a plurality of lenticular elements 12 of saw-tooth configuration formed along one edge thereof to direct light edgewise and substantially uniformly into the section If) from a relatively concentrated incandescent light source l3 positioned approximately in the plane of the section 10 but spaced a short distance therefrom.

The dial may include a, framing or escutcheon section [4 integral with and surrounding the planar section It. It is convenient for low-cost mass production purposes to fabricate the planar section In and the escutcheon section I4 as an integral unit by a molding process. A suitable material for this purpose is an acrylic plastic such as a polymerized methyl meth-acrylate resin of which those sold under the trademarks Plexiglas and Polysterene are typical. The escutcheon section I4 preferably is rendered opaque by coating its forward surface IS with a suitable pigmented lacquer of any desired pigment color.

Referring now to the enlarged fragmentary view of Fig. 3, the light source I3 is positioned a distance d perpendicular to the edge of the section l0 and the lenticular elements I2 begin a distance a: from the perpendicular approximately equal to d tan 40 when the section I0 is formed of an acrylic plastic. Each lenticular element [2 has a planar surface portion I6 which forms with respect to incident rays of light falling thereon from the light source an angle of approximately 50 so that all incident light rays on the portion l6 are within an angle not exceeding approximately 40 with respect to a perpendicular from the source 13 to the plane of the surface portion l6. Each of the lenticular elements I2 also includes a planar surface portion I T which includes the light source I3 in the plane thereof so that the portion I! does not cause a shadow on the surface of the portion iii of an adjacent lenticular element. The number of lenticular elements used in a particular application is selected such as to provide substantially uniform edgewise illumination interiorly of the section It), and as indicated in Fig. 3, this may require a larger number of lenticular elements on one side of the light source l3 than on the other where the light source is offset to one side of the center of the dial.

A dial embodying the present invention is characterized by quite uniform internal illumination when illuminated from a single relatively concentrated light source, and yet is one of relatively simple and inexpensive construction suitable for low-cost mass production techniques. At the same time, the dial is quite suitable from the 3 standpoint of pleasant and attractive styling considerations as is particularly desirable for radio and television receiver applications.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be apparent to those skilled in the art that various changes and modification-S may be made therein without departing from the invention. Consequently, the appended claims should be interpreted broadly, as may be consistent with the spirit and scope of the invention.

What I claim is:

l. A dial comprising a planar section of transparent material having a plurality of lenticular elements formed along one edge thereof todirct light edgewise and substantially uniformly into said section from a relatively concentrated'light source positioned approximately in the plane of said section but spaced from said one edge thereof.

2, A dial comprising a planar section of transparent material having a plurality of lenticular elements of saw-tooth configuration formed along the one edge thereof to direct light edgewise and substantially uniformly into said section from a relatively concentrated light source positioned approximately in the plane of said section but spaced from said one edge thereof, 7 p I 3, A dial comprising a planar section of clear polymerized methyl methacrylate resin having an edge serrated to provide lenses of saw-tooth configuration to directlight edgewise and substantially uniformly into said section from a relatively concentrated light source positioned approximately in the plane of said section but spaced from said one edge thereof. v

4. A dial comprising a planar section of clear polymerized methyl methacrylate resin having an edge serrated to provide lenses of saw-tooth con- 4 figuration to direct light edgewise and substantially uniformly into said section from a relatively concentrated light source positioned approximately in the plane of said section but spaced from said one edge thereof, each of said lenses having a first planar surface portion which includes said light source in the plane thereof and a second planar surface portion'forming an angle not substantially less than-50 with respect to incident rays of light falling thereon from said source.

5. A dial comprising a planar section of transparent material having indicia on one side thereof and having a plurality of lenticular elements of saw-tooth configuration formed along one edge thereof to direct light edgewise and substantially uniformly into said section from a relatively concentratedlight source positioned approximately in the plane of said section but spaced from said one edge thereof, and an opaque framing or escutcheon'section integral with and surrounding said planar section. EDGAR K. NAUTH.

References Cited in the file of this patent UNITED STATES PATENTS 

